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What is CNC Milling? Types, Process and Operation
What is CNC Milling? Types, Process and Operation
CNC milling is a cutting method which is a feature of Computer Numerical Controlled (CNC) Machine. It has been in use for the last two centuries. During the time of industrialization, it was the most used and advanced machining technique. Now it has become a very critical cutting. This article is all about CNC milling that will increase your knowledge and expertise. So, let’s start with its brief introduction:
What is CNC Milling?
CNC milling is a machining technique for manufacturing complex parts in different industries. The cutting or removal of the excessive material results in desired shapes. Multiple rotaries cutting tools are used for the cutting process and they are controlled by a CNC program i.e. CAM (Computer-aided Manufacturing) software
What is a CNC Milling Machine Used for
CNC Milling Machine is used in manufacturing industries to make complex parts such as airframe parts, landing gear, transmission cases, orthopaedic implants, heat sinks, missile guidance systems customized jewellery etc. All these parts require tight tolerance and precision which precision CNC milling provides. A CNC mill is different from a lathe, it rotates the cutting tools to machine parts.
The Role of Computer Numeric Control (CNC)
The important features such as automation during the work are due to this Computer Numeric Control component. This component works using CNC programs such as CAM software. All the data like spindle speed, cutting rate, changing of the tools etc. is fed into this system.
CNC Milling Process
The Milling Process starts with the preparation of the 3D design by using CAD software. The machine cannot read a 3D design which is why it is converted into a readable format using CAM software. Let us provide you with a step-by-step guide on how a CNC machine works.
Step-by-Step Guide: How CNC Milling Works
1.The first step you will do is to design a 3D image of the required part then converting into a readable format through CAM software.
2.Select appropriate cutting tools.
3.Fix the workpiece firmly in the workpiece holder .
4.Feed the spindle speed, cutting rate, axis etc. in the software .
5.Turn on the machine and you can start the process.
During processing, you should use a coolant as well because cutting off material generates heat within the sample which can damage your workpiece.
CNC Milling Software
CNC Milling Software is used to convert the given 3D designs of the workpiece into readable instructions for the machine. Then through programming, the speed of tools, tool path optimization etc. is stored in the software which then controls the tools according to the instructions automatically during work.
Vertical Milling Machines
You will see by using a vertical milling machine, the rate of precision is high. The main reason for high precision is the ease of machining the workpiece because the direction of the spindle is perpendicular to the workpiece.
5-Axis CNC Milling Machines
This machine is made for the manufacturing of complex designed parts with high precision. The parts such as aircraft parts which have very high safety standards are produced through this version of the machine. The cutting tools can machine the parts in the 5-axis so the production rate is high as well.
Universal and Turret Milling Machines
- Universal milling machine the moving cutting tool makes a complex design of the stationary workpiece.
- The workpiece is prepared through a stationary cutting tool.
CNC Control Panel
This part has keys on it as you can see in the image. These keys control the machine for instance, that red button is used to stop the machine in an emergency.
Spindle
The spindle contains those cutting tools which cut the material from the workpiece.
Tool Holders and Automatic Tool Changers (ATC)
Tool holders as the name itself tells, they hold different types of cutting tools.
These are two different components of a CNC milling machine with different functions. Tool holders hold the cutting tools and automatic tool changer (ATC) helps in changing the cutting tools automatically.
Workholding Systems
These systems are involved in holding the workpiece firmly and maintaining accuracy.
CNC Milling Machine Operation
Here, you will read about some important milling operations:
Face Milling
This process is used for the machining of flat workpieces, pockets etc. You will get a fine surface finish and tight tolerance. Its working is the same as of vertical CNC milling.
Plain Milling
The overall procedure of working is the same as of face milling. The only difference is the movement of the cutting tool which is parallel to the workpiece. To get the best results, your workpieces should be flat surfaces.
Angular Milling
In this operation, the spindle is perpendicular to the workpiece, but a cutting tool is placed at an angle to the workpiece. If you intend to make complex shapes, angled surfaces, grooves etc. you need to perform an angular milling operation.
Form Milling
It comes up with one limitation that is it is not a good choice for low-level production. It is a specialized type of CNC milling process which is used to make advanced and contoured shapes on the workpieces by using rotating tools.
Materials of CNC Milling Machining
A CNC machine has the freedom to work with any material, it can machine composites, metals, plastics etc. with excellent accuracy.
End Milling
It is a versatile milling process used to machine slots, shoulders, die cavities etc. The one main limitation is, that end mills are very expensive.
Benefits of CNC Milling
Some of the key advantages are given below:
1.It is a cost-effective manufacturing method because there is no need to hire many people to operate the CNC milling machine.
2.CNC milling is a reliable tool for preparing complex parts without any risks of errors due to the automation feature. Precision CNC milling and customized tool path optimization are the important features to make critical parts i.e. turbine blades.
3.Since you will not physically remain in contact with the workpiece machining, that is why they are very low chance that you will suffer any injury.
4.A CNC milling machine can operate 24/7 continuously because of the CNC program. Automatic Tool Changing (ATC) is another feature behind this advantage.
5.Daily cleaning and inspection are enough to keep the CNC milling machine working. It does not need maintenance a lot.
6.5-Axis CNC milling machine is the most advanced version of milling machines and is used for intricate complex parts.
Metals CNC Milling
The metals which are tough and machinable such as Aluminium, low carbon steel, stainless steel, Copper, titanium etc. are very easy to machine on a CNC machine. Because during work, the CNC machine puts force on the workpieces due to which hard and brittle metals like high carbon steel, and martensitic steel can fracture, that’s why only tough and ductile materials should be chosen for better results.
Plastics CNC Milling
For CNC milling operations, those plastics are suitable and have suitable strength for machining. Plastics like polyvinyl chloride, Polyether ether Ketone etc. are thermosetting plastics and have suitable strength for machining and are commonly used in industries to make bearings and piston parts.
